5. Generating energy for household use from biological
waste could be the first and the simplest step towards
replacing fossil fuels in everyday use.
In this presentation, I will describe in detail a solution
where kitchen waste is used to generate biogas for
cooking.
Introduction
6. Concept
Recycling kitchen waste to produce fuel for cooking.
Kitchen waste (biomass) has stored chemical energy
derived from solar energy by photosynthesis.
Biomass gets converted into methane by anaerobic
bacteria.
Methane generated in this way is a green fuel.
8. Advantages
Generation of green fuel from waste
Renewable form of energy which is carbon neutral.
The amount of CO2 generated in the process is equal
to the amount used up by the same biomass while
alive.
The slurry generated is an excellent manure.
Improperly disposed of kitchen waste would
otherwise lead to fly nuisance and various health
hazards.
No safety issues involved as methane generated is
not compressed.
9. Step-by-step design: (You can do it yourself!)
Materials:
200 litres digester with an airtight lid
Culture, made of cow dung and water (50 : 50),
developed in anaerobic environment
200 litres expandable balloon to fill biogas
Funnel (to feed waste in the digester)
Pipe with connectors
Container for slurry
Biogas stove
10. Step 1:
A container made of thick
plastic was taken and two
circular holes were cut in
the lid of the container
Bigger opening is for
feeding kitchen waste in
the digester and the
smaller opening serves as
the outlet for leading the
gas into an expendable
reservoir
11. Step 2:
An outlet for the
slurry has been
made to collect the
excess culture which
comes out while
feeding the digester
with the kitchen
waste
12. Step 3:
Adhesive is applied
all around the
feeder assembly to
make it leakproof
The assembly is
screwed tightly onto
the lid
13. Step 4:
Pipe connections were made to
connect the digester with the
reservoir and subsequently to
the gas stove
14. Step 5:
The picture on top shows
the digester filled with
the required culture to
produce methane
Digester on the left
produces methane and
the reservoir on the right
gets filled with the gas
15. Step 6:
These pictures show
the burning of
methane with blue
flame used for
cooking on the gas
stove
17. Safety Features of the device
Pressure inside an LPG cylinder at room temperature
is approximately 6 – 10 bar (6 bar = 4560 mm Hg /
torr) depending on room temperature. This high
pressure is due to compression of propane. This
process of compression helps gas to last for a longer
time, but makes LPG cylinders relatively dangerous.
Pressure within the fully inflated 200 litres capacity
balloon in the biogas system is virtually negligible
because it is not compressed. Due to this, it is not
hazardous. It can never explode or catch catastrophic
fire.
18. Hurdles
It takes about a month for the bacterial culture to
stabilize.
The basis of biogas generation needs to be
understood by the user.
It takes time to find the exact amount of kitchen
waste to be fed in the digester: excess amount will
make it acidic and less amount will result in
inadequate generation of methane
During winter season it may not generate sufficient
methane as it requires optimum temperature
(more than 37 degrees Celsius).
19. Precautions and Solutions
Learn to feed right amount of kitchen waste in the
digester daily.
We need to maintain the PH level of 6.5 – 8 to
generate methane. When the conditions within the
digester are not optimum, PH level drops and the
digester becomes acidic.
In this case, add lime or any alkali which neutralizes
the acid to restore the PH level. Check the PH level
with the litmus paper till it comes back to normal.
Stop feeding kitchen waste at this this time, and wait
for two to three days.
20. Conclusion
With the use of biogas, our consumption of LPG
reduces significantly, saving this non-renewable
fossil fuel.
It cuts down the fossil CO2 emissions associated
with the burning of LPG.
Biogas is carbon neutral.
Also an economical source of fuel.